1. Field of the Invention
The present invention relates to a heat exchanger core set in a heat exchanger of the type in which the heat exchange is carried out between a fluid flowing through a pipe and a heat medium outside of the pipe and more particularly a heat exchanger core best adapted for use in the evaporators of the air conditioning devices and refrigeration devices, the chemical apparatus the electronic equipment and the like.
2. Description of the Prior Art
The heat exchanger core of the type described above is assembled with a header for flowing a fluid through the core so as to construct a heat exchanger and it is known a core called a heat transfer pipe in which the heat exchange is effected between a fluid flowing through a pipe and another fluid flowing outside of the pipe.
FIGS. 1 and 2 illustrate conventional heat exchanger cores, respectively, in which a plurality of fins 4A and 4B are joined to the upper wall 2 and the lower wall 3 in opposing relationship with each other of a pipe body 1 having a flat rectangular cross sectional configuration are spaced apart from each other by a suitable same distance. In the case of the heat exchanger core illustrated in FIG. 1, the fins A and B are extended in the direction perpendicular to the direction in which a fluid flows through the pipe body 1 while in the heat exchanger core illustrated in FIG. 2 the fins 4A and 4B are extended in the direction in which a fluid flows through the pipe body 1. The fin 4A extended from the upper wall 2 and the opposing fin 4B extended from the lower wall 3 are in vertically coplanar relationship with each other and in the vertical direction, a predetermined space 5 is defined between the each fin pair 4A and 4B extended from the upper and lower walls 3 and 4, respectively.
In the cases of the conventional heat exchanger cores of the types illustrated in FIGS. 1 and 2, respectively, the heat transfer area of the inner surfaces of the pipe body 1 is increased, thereby increasing the heat transfer quantity, but the heat exchanger core of the type illustrated in FIG. 1, a fluid which flows through the pipe body 1 impinges against the fins 4A and 4B, resulting in vortex flows so that there arises the problem that compared with the increase of the heat transfer coefficient, the pressure loss is increased a little. In the case of the heat exchanger core of the type illustrated in FIG. 2, a plurality of fluid streams only flow straightly along the fins 4A and 4B in the pipe body 1 so that there arises the problem that heat transfer will not so increased even though the heat transfer surfaces are increased because the heat transfer coefficient is decreased.
Japanese Laid-Open Patent No. 113998/1981 or No. 117097/1981 discloses another type of a heat exchanger core in which a plurality of spiral grooves are defined in parallel with each other over the inner surface of a cylindrical pipe body.
However, in the case of the heat exchanger core of the type described above, due to a plurality of parallel spiral grooves within the pipe body, many vortex flows are formed within the pipe body so that there arises the problems that the pressure loss becomes higher and that the heat transfer coefficient is increased.
Furthermore as a heat exchanger core used in the above-mentioned electronic equipment, well known in the art is the so-called heat sink which dissipates heat from the heat generation component parts such as transistors, diodes, thyristor and the like which are mounted on an electronic device.
FIG. 3 illustrates a conventional heat exchanger core of the type just described above. Electronic component parts which generate heat such as transistors, diodes, thyristors and the like 7 are threadably mounted on the upper surface of a metal base 6 of a core by means of screws 8, whereby a heat exchanger is constructed. A plurality of parallel elongated grooves 9 are formed in the undersurface of the base plate 6 and are spaced apart from each other by a suitable distance so that the upper side edges of rectangular fins 10 are snugly fitted into the elongated grooves 9.
In the case of the heat exchanger of the type illustrated in FIG. 3, a plurality of air streams flow through the spaces defined by the adjacent fins 10 so that heat generated by the heat generating component parts 7 and transferred by conduction from the base plate 6 to the fins 10 is dissipated into the surrounding air.
However in that case, the air which flows between the adjacent fins 10 will not be vortex flow, but will be laminar so that there arises the problem that the heat transfer coefficient is low and therefore the heat transfer quantity by convection is not increased even though heat transfer surfaces are increased.